3uk_mishra2001@yahoo.com, Department of Veterinary Anatomy and Histology, Orissa University of Agriculture and Technology, Bhubaneswar, 751003 (Orissa).
1Department of Veterinary Anatomy, G.B. Pant University of Agriculture and Technology, Pantnagar, 263145, (Uttarakhand).
2Institute of Biotechnology, Nainital, (Uttarakhand) INDIA.
Histomorphological observations were made on the thymus and bursa of Fabricius, spleen and caecum of 130 chicks aged day 1 to day 60 at 5 day interval. In day old chicks the thymic lobes had a thin capsule and its thickness increased with age. The collagen fibers were scanty in the trabeculae, venules and moderate in arterioles of the thymic medulla. The arteriolar wall revealed thick reticular bundles and venules had few fibers. The quantity of the reticular fiber increased with age and 50 days of age. The cortical zone was larger than the medullary region on the day of hatching. By 20th day the medulla was larger than the cortex. The frequency of thymic corpuscles, myoid cells, and vesicles significantly increased with age. Four kinds of vesicles were evident in the thymus viz. (1) Large ovoid vesicles with dense eosinophilic body, (2) Medium ovoid vesicles with mild eosinophilic body, (3) Large ovoid vesicles devoid of luminal content and (4) small oval or irregular vesicles devoid of luminal content. The bursal follicle developed as epithelial buds by proliferation, condensation and invagination of epithelial cellular mass which continued up to 10 days of age. Reticular fibers were few in the follicular cortex and scanty in the medulla. By 35th day the follicles were surrounded by a 2–3 cell thick highly granular eosinophilic cellular layer with dense oval or elongated nuclei.
Chicken, Thymus, bursa of Fabricius, Histomorphology, Development
